I flat pick the 5 String for some tunes in an Irish band I have been in for 18 years. I have learned that the stiffest and most pointed pick I can find (Tortex) has the best tone and is the fastest pick I can use. This works for me, maybe not others. Thin picks are noisy and they tend to be slower because you are further away from the string by the time they sound the string and consequently you have further to go back. How much further? Very tiny particles of an inch but in the world of strings and plectrums these are considerable.

Give the heavy pointed white Tortex picks a try.

Don